1. Field of the Invention
The present invention relates generally to fluid reaction surfaces, and more specifically to a thin rotor blade.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
A turbomachine, such as a compressor in an aircraft gas turbine engine, includes an airfoil portion with leading edge and trailing edge portions extending from the airfoil portion. Rotor blades have been made from a single material in the early prior art. In order to improve on the performance of the turbomachine, the rotor blades have been made from composite materials in order to lighten the blade as well as increase the blade's strength. In some situations, the leading edge or trailing edge of the blade is made of a separate material in order to reduce damage from a foreign object striking the edge during rotor blade operation. In a small compressor, a blade without a sharply defined leading or trailing edge leads to a significant loss in performance.
In a rotor blade used in a compressor, the leading edge and trailing edge need to be thin or sharp in order to produce a high performance in the compressor. A prior art rotor blade made from a composite material such as a composite laminated material requires a relatively large radius to wrap the laminated material around the edges of the blade. U.S. Pat. No. 3,762,835 issued to Carlson et al on Oct. 2, 1973 and entitled FOREIGN OBJECT DAMAGE PROTECTION FOR COMPRESSOR BLADES AND OTHER STRUCTURES AND RELATED METHODS discloses a composite compressor blade having a leading edge portion formed from a fine wire mesh clad in nickel. Because of the laminates, the leading edge of the blade is rounded and not sharp.
U.S. Pat. No. 3,758,234 issued to Goodwin on Sep. 11, 1973 and entitled FIBER BLADE WITH LEADING EDGE REINFORCEMENT discloses a rotor blade in a gas turbine engine in which two strips of metal are joined together at the leading edge over laminations of carbon fiber reinforced resin that form the made body of the blade. The leading edge of the blade is rounded and therefore does not provide the sharp edge as in the present invention.
In a rotor blade made from a fiber reinforced composite material such as carbon fiber embedded within a polyester resin, sand particles will severely damage the leading edge portion of the blade. This type of blade is made of strong and lightweight material, but cannot withstand the damage from the sand particles.
It is therefore an object of the present invention to provide for a small rotor blade that will have a sharp leading or trailing edge in order to provide higher performance over the cited prior art references, and to have the lightweight and strength required to withstand damage from sand particles or other foreign objects that would damage the leading or trailing edge.